The use of polysaccharides or sugars in liquid form, such as honey, is known to be effective as a dressing for wounds, burns and skin ulcers. Benefits include that inflammation, swelling and pain are quickly reduced, that sloughing of necrotic tissue occurs without the need for debridement, and that growth of tissues to repair the wound is stimulated. As a consequence, healing occurs rapidly with minimal scarring, and often without any necessity for skin grafting. In addition, the use of solid polysaccharides or sugars such as cane sugar is also known. Cane sugar, which contains organic elements that are known to improve wound healing, is more concentrated in sugars than honey (honey contains more water than solid cane sugar).
It is well known that the ability of the sugar to debride and loosen necrotic tissue in the wound is driven by the effect of the exertion of osmotic pressure. This osmotic pressure is directly related to the concentration of sugars at the wound surface. Thus it would be beneficial for the sugar to be as pure as possible (and consequently unmixed with any other non sugar element) when it comes into contact with the wound in its role as a wound dressing. However, both liquid and solid polysaccharides, such as honey and cane sugar respectively, present usability issues for a wound dressing, and appropriate delivery systems are required.
Assuming that it should be almost pure sugar that comes in contact with the wound implies that this almost pure sugar should be in a form that is deliverable to a wound. In this context pure honey is not a suitable physical form. This is because pure honey flows too fast and, if applied to a wound, is more likely to spill out of it, than stay in it, and this effect is only minimally improved upon via the use of a secondary dressing such as gauze. Likewise, pure crystalline or powder sugar has usability issue. For example, powdered sugar is messy in terms of application in a wound and a secondary bandage is most certainly needed. Accordingly, it would be beneficial if some means were to be found to attach or adhere cane sugar to a secondary dressing but without the use of sugar diluting adhesives or any non-sugar matter.
In addition to the use of polysaccharides in the use of wound treatment, it is known that MMPs, which are part of the larger family of metalloproteinase enzymes, play an important part in wound healing. Although MMPs have the important role of breaking down proteins so that new tissue forms, when MMPs are present in a wound bed at too high a level, for too long a time, and in the wrong places, they begin to degrade proteins that are not their normal substrates. This can result in the unwanted destruction of beneficial proteins, such as growth factors, receptors and ECM proteins, that are essential for healing, and so ultimately impair healing. Substantial evidence has amassed that MMPs in general are highly elevated in wounds with delayed healing compared to acute healing wounds as discussed, for example, in Wounds International, “MMPs Made Easy” (Vol. 1, Issue 1, November 2009), which is incorporated herein by reference. The potentially damaging effects of these high levels is compounded by the fact that tissue inhibitors of metalloproteinases (“TIMPs”) levels in chronic wounds are generally slightly lower than in acute wounds.
The most preferred methods of cleansing of necrotic tissue are often surgery, curettage or sharp debridement. However, it may not always be possible to use one of these methods on patients who are not suitable candidates for such fast and immediate debridement. Collagenase enzyme, a MMP, is itself sometimes used to promote debridement, thereby incurring the negative effects of MMPs in the wound. Accordingly, it is advantageous to provide an improved method of debridement that does not introduce MMPs into the wound.
U.S. Pat. No. RE42,755 to Molan describes a wound dressing incorporating a honey composition that is at least 50% honey and mixed with a gelling agent to render it formable, pliable, flexible and moldable. While this design does allow a liquid polysaccharide (honey) to be more conveniently delivered, the intimate mixing with the gelling agent causes the sugar concentration at the wound to be lowered than it would be without mixing with the gelling agent. In addition, Molan does not mention the MMP suppression effect of honey.
U.S. Pat. No. 4,844,898 to Komori, U.S. Pat. No. 3,767,784 to Gluck, and U.S. Pat. No. 4,401,651 to Knutson also discuss polysaccharide compositions for use with wound dressings. Each of these references fails to recognize that the efficacy of polysaccharides is driven by the exertion of osmotic pressure. This osmotic pressure effect causes wound exudates to flood in from deep within tissue into the wound site, dissolving necrotic tissue and cleansing the wound. Accordingly, these references do not teach that the dilution of the polysaccharide by non-active ingredients, such as viscosity enhancing components, absorbent components, or gelling compounds, will reduce the osmotic pressure correspondingly. In addition, these patents were written prior to the introduction of the concept that MMPs are responsible for wound chronicity.
Accordingly, a need exists for a composition that allows the effective application of polysaccharides in high concentrations to a wound surface. A need also exists to for a composition that provides non-sharp debridement while also controlling the level of MMPs present in the wound.